The Bob Hannon book is probably the "bible" on Postwar motor troubleshooting. All of these measurements are in there. [I often wonder how many motors he took apart, to come up with those normative values!] Anyhow, it's an invaluable resource for this sort of thing.
I would be surprised though to learn that this is the cause. I've messed with Postwar since my teens, and I've seldom come across a burned-out armature coil. It's good to know that there are folks who rewind them. But on many steam locos, removal and reinstallation is a pro-level repair. Check the basics first!
